Drum filters are often used to filter the wash fluid at the rinse and wash stage of a phosphate line in an automobile assembly plant. Such drum filters generally comprise a perforate drum encircled by a renewable filter media. Fluid flows from the outside of the drum through the filter media to the inside of the drum. Discharge of the fluid from the inside of the drum is effected by passing the liquid through the center of a tubular discharge shaft. The filter media generally comprises non-woven fibers such as "DACRON," nylon, "ORLON," etc.
One problem inherent in all drum filters heretofore known and used is the difficulty of applying fresh filter media to the periphery of the filter drum, rotating the drum to effect advancement of the media, and removal of the wet clogged filter media from the drum.
Another aspect of the problem relates to a means for retaining the media on the drum while rotating the drum. For example, rotation of the drum and the media by a chain drive often caused tearing and bunching of the filter media. Pulling the media through the filter by rerolling the media has the inherent disadvantage of requiring careful tension and speed control of the drum. Stated in another manner, no fully satisfactory solution to the problems of applying the filter media to the drum, rotation of the drum and concomittant advancement of the media, and handling of the wet, soiled filter media has been presented heretofore.